Salts of boron-hydride anions and boron containing organic cations and method of their preparation



United States Patent 3,383,399 SALTS 0F BORON 'HYDRIDE ANIONS AND BORON CONTAINING ORGANIC CATIONS AND METHOD OF THEIR PREPARATION Stanley Frank Stafiej, Springdale, and Edward Andrew Takacs, South Norwalk, Conn., assignors to American 1(slyanamid Company, Stamford, Conn., a corporation of ame No Drawing. Filed Mar. 9, 1964, Ser. No. 351,586 7 Claims. (Cl. 260-453) ABSTRACT OF THE DISCLOSURE Salts of boron-containing cations and boron-containing anions, their method of preparation by the metathetical reaction of othersalts of boron-containing cations with boron-hydride salts and their use as high energy solid rocket propellant ingredients, burning rate modifiers for rocket propellants, and boron-containing gasoline additives are disclosed.

This reaction may be represented by the following equation:

wherein [Z and [Z are each ligands selected from the group consisting of tertiary amines in which the nitrogen atom is bonded only to carbon atoms and not more than one nitrogen atom of another amine radical, nitriles, dialkyl sulfides, and tertiary phosphines in which the phosphorus is bonded only to carbon atoms; wherein M is a boron-hydride anion, such as B H B H B I-I 12' 12 io if, 4", lo ia' z fa BH13'NH3 and B H CEN=; and n is a positive integer equal to the valence of the boron-hydride anion.

The boron-containing cation useful for performing the reaction of the present invention may have associated with it any anion which will not interfere with the above reaction, such as the chloride, bromide, fluoride, nitrate, chlorate, sulphate, chloroplatinate, triiodide, hexafluoro metaantimoniate, tetraphenylborate, tetrachloroborate and fluophosphate anions, although it is generally preferred that the anion be the fluoroborate or perchlorate anion since the fluoroborate and perchlorate of this cation can be prepared directly from readily available starting materials by the processes described and claimed in copending applications Ser. Nos. 351,583, now US. Patent No. 3,305,555, issued Feb. 21, 1967 and 351,582, now US. Patent No. 3,296,274, issued Jan. 3, 1967, filed concurrently herewith by Stafiej and Takacs, and Stafiej and Carval-ho, respectively, and assigned to the assignee of the present application.

The boron-hydride anion useful for performing the reaction of the present invention may have associated with it any cation which will not interfere with the above reaction, such as potassium, sodium, lithium, ammonium, calcium, barium, zinc, tetramethylammonium, or triphenylmethylphosphonium, etc. Thus, illustrative of the boron-hydride salts useful in the process of this invention are the following: (CH NB H KB H Ca(BH The nucleophiles or ligands [Z and [2,] may be any of the ligands described in the aforesaid copending ap- 3,383,399 Patented May 14,1968

carbon radicals or substituted hydrocarbon radicals. For

example, they may be lower alkyl (e.g., methyl, ethyl, npropyl, isopropyl, butyl, etc.), aryl (e.g., phenyl, biphenyl, naphthyl, etc.), aralkyl (e.g., benzyl, xylyl, etc.), alkaryl (e.-g., tolyl, dimethyl-phenyl, ethyl-phenyl, cumenyl, etc.) or substituted forms thereof (e.g., containing one or more halogen, alkoxy, ester, thioether, etc..

groups). Also, the tertiary amine may have the formula in. R5

its- N wherein R and R are hydrocarbon radicals or substituted hydrocarbon radicals. For example, R may be the same as previously described for R R and R and R may be a bivalent radical which, when joined to the nitrogen atom by both valences, forms a heterocyclic ring (e.g., pyrrole, pyrrolidine, pyrroline, piperazine, piperidine, pipecoline, etc.). Further, the tertiary amine may have the formula wherein R, is a hydrocarbon radical or substituted hydrocarbon radical which, in conjunction with the nitrogen atom, forms a heretocyclic ring (e.g., pyridine, naphthyridine, quinol-ine, pyrimidine, bipyridyl, etc.). Additionally, the tertiary amine may be a hydrazine derivative having the formula RQN HIN/ v wherein R and R may be the same as R R or R, above.

Also, the ligand can be any of the various nitriles, e.g., lower alkylnitriles (acetonitrile, propionitrile, butyronitrile, etc.), cyanogen, lower alkylene dinitriles (malononitrile, succinonitrile, glutaronitrile, etc.). Further, the ligand can be a dialkyl sulfide, e.g., dirnethyl sulfide, ethyl methyl sulfide, diethyl sulfide, substituted forms of the foregoing, etc.

Additionally, the ligand can be a tertiary phosphine in which the phosphorus atom is bonded only to carbon atoms of hydrocarbon or substituted hydrocarbon radicals and which may have any of the formulae wherein 9, 10 11, 12, 14 15, 1'b 18, 19, and R are monovalent hydrocarbon radicals which may be the same or different in any given formula and R R R and R are bivalent hydrocarbon radicals. These monovalent hydrocarbon radicals may be any of those previously described for R R or R of Formula II. The bivalent hydrocarbon radical R can be any one which, when joined to the phosphorus atom by both valences, forms a heterocyclic ring (e.g., tetramethylene, pentamethylene, CH -CH -CH CH etc.). The bivalent hydrocarbon radicals R R and R may be lower bivalent alkyl groups (e.g., methylene, ethylene, propylene, butylene, etc.) and, preferably, R and R together with two phosphorus atoms of Formula IX should add up to a five or six atom heterocyclic ring for maximum stability. R may also be a bivalent aryl, alkaryl, or aralkyl group (e.g., o-phenylene, m-phenylene, p-phenylene, o-xylylene, m-xylylene, pxylylene, toluylene. naphthylene, etc.). Illustrative of ligands useful in the process of this invention are the following:

N-CzH CH3CEN, NEC-CEN, NEG-CHz-CEN, (CH S, a' z s, s)3 d s i sh,

All of the foregoing nucleophiles or ligands have been listed in their simplest forms, but substituted forms thereof may also be used. Thus, they may contain fluorine, chlorine, bromine, or iodine atoms, ether linkages, ester linkages, alkoxy groups, thioether linkages, and other substituents attached thereto provided they do not adversely alfect the desired reaction. Also, they may include wherein Y represents a hydrocarbon or substituted hydrocarbon group, X represents --O or --S--, and L represents a hydrocarbon or substituted hydrocarbon group. For example, the ligand may be -l| IH ;i-IIH CHs--OCHz; NECCHr-CO-CH CH3 T -1;1E -1I\IH. CH3COCHrCH 0CCH3; (oH3)=oIId-o-O.-.H5

etc.

These boron-containing cations may be prepared from readily available starting materials in accordance with the teachings of the aforesaid copending applications 4 1 Ser. Nos. 351,583, now U.S. Patent No. 3,305,555, issued Feb. 21, 1967; 351,582, now U.S. Patent No. 3,296,274, issued Jan. 3, 1967; and 351,584, now U.S. Patent No. 3,341,582, issued Sept. 12, 1967.

In application Ser. No. 351,583, now U.S. Patent N0. 3,305,555, issued Feb. 21, 1967, one method for preparing the boron-containing cations shown on the left side of Equation I above is taught wherein a tertiary amine-.

borane is reacted, under anhydrous conditions, with a trityl salt and a nucleophile or.ligand. In application Ser. No. 351,582, now U.S. Patent No. 3,296,274, issued I an. 3, 1967, another method for preparing such cations is taught wherein a borohydride salt is reacted, under anhydrous conditions with at least two equivalents of a trityl salt and at least two equivalents of a nucleophile or ligand. In application Ser. No. 351,584, now U.S. Patent No. 3,341,582, issued Sept. 12, 1967, yet another method of preparing such cations is taught wherein boron-containing cations containing at least one nitrole ligand are reacted under anhydrous conditions with alcohols or mercaptans.)

The boron-hydride anions useful for performing the reaction of the present invention may be prepared from various starting materials by various processes. Illustrative of such preparations are the following:

The B H anion can be prepared by reacting together at room temperature deca-borane with an aqueous solution of at least two molar equivalents of an alkalimetal hydroxide to form an intermediate compound which can then be reacted at room temperature, while still in the solution wherein it was formed, with a mineral acid in an amount which is one molar equivalent less than the molar equivalents of base employed to produce the B9H14 anion as taught in pending application Ser. No. 219,367, filed Aug. 22, 1962 by Benjamin, Stafieji and Takacs and assigned to the assignee of the present application.

The B 11 anion can be prepared by reacting together pentaborane-9 with a basic material (such as an alkalimetal hydroxide, carbonate, methoxide, or ethoxide) in the presence of liquid water or alcohol as taught in pending application Ser. No. 343,173, filed Nov. 16,-

1962 by Carvalho and Shust and assigned to the assignee of the present application.

The B H anion can be prepared by the method described in letters by Hawthorne and Pitochelli, J.A.C.S., 81, 5519 (1959) and J.A.C.S., 82, 3228 (1960).

The B H anion can be prepared by the method described in a letter by Pitochelli and Hawthorne, J.A.C.S. 82, 3228 (1960).

The B H anion can be prepared by the method described by Muetterties in Inorg. Chem, 2, 647. (1963).

The EH anion is a commercially available product in the form of its alkali-metal salts.

The B I-I -N H; anion can be prepared by reacting together, in an aqueous medium, decaborane, hydrazine, and a strong base (such as alkali-metal hydroxide, hydrazine, guanidine, and mono-, di-, and tri-aminoguanidine) as taught in application Ser. No. 214,797, now U.S. Patent No. 3,281,219, issued Oct. 25, 1966, filed Aug. 1, 1962, by Takacs and assigned to the assignee of the present application.

The B H -NH anion can be prepared by reacting together decaborane and a large excess of ammonium hydroxide (about 12 to about 15.2 moles of ammonium hydroxide per mole of decaborane) at reduced temperature (about -20,C. to about +5 C.) as taught in abandoned application Ser. No. 220,590, filed Aug. 22, 1962 by Carvalho and assigned to the assignee of the present application.

The B10H13CEN= anion can be prepared by the method described byKnoth and Muetterties in J. Inorg. and Nucl. Chem., 20, 66 (1961).

It is usually preferred to perform the reaction of this invention in the presence of an inert solvent which may be water, alcohol, etc. The reaction occurs easily and rapidly at atmosphere pressure and at room temperature or below merely upon mixing the various ingredients together. However higher or lower temperatures and pressures may be used when desired. For example, this reaction can be performed at pressures of from about 100 mm. Hg to about five atmospheres and at temperatures of from about 78 C. to about 100 C.

The two reactants may be used in stoichiometrical proportions (i.e., one equivalent of boron-containing cation for each equivalent of boron-hydride anion) or an excess (0.1 to 100 mole percent or more) of either may be used.

Examples of products of the present invention are:

etc.

The compounds of this invention are useful as high energy solid rocket propellant ingredients, burning rate modifiers for rocket propellants, and as boron-containing gasoline additives.

For a clearer and more detailed understanding of the nature of the present invention, reference may be had to the following examples which are intended as illustrative only and not as limitations on the invention.

Example 1.Preparation of CH N H A solution of 186 mg. (1 mrnole) of (CH NB H in ml. of methanol was added to a solution of 232 mg. (1 mmole) of [CH (CH O)C=NHBH N(CH ]BF in 10 ml. of methanol. After a short induction period, white dandritic crystals of (CH NBF settled from solution. The solution was chilled in ice for minutes and filtered to yield 120 mg. (75% yield) of material. Evaporation of the filtrate to dryness yielded 220 mg. (86% yield) of a light yellow solid, M.P. 85-96 C. Three recrystallizations from methanol-water raised the melting point to 97 C.

Analysis.Ca1culated for C H N B O: ,C, 28.09; H, 12.57; N, 10.92; B, 42.18. Found: C, 28.48; H, 12.24; N, 11.10; B, 46.78.

Example 2.--Preparation of 6 A solution of 400 mg. (2 mmoles) of in 5 ml. of water was added to a solution of 820 mg. (2 mmoles) of KB H -dioxanate in 10 ml. of water. The white precipitate formed was filtered off and air dried to yield 360 mg. (80.2% yield) of product.

We claim:

1. A compound having the formula 5. A process for preparing organic boron-hydride salts of boron-containing cations comprising reacting, at

' a pressure of about 100 mm. Hg to about 5 atmospheres and a temperature of from about -78 C. to about C., a salt of a boron-containing cation with a salt of a boron-hydride anion.

wherein [Z and [2 are each ligands of tertiary amines in which the nitrogen atom is bonded only to carbon atoms and not more than one nitrogen atom of another amine radical, nitrilcs, di-alkyl sulfides, or tertiary phosphines in which the phosphorus atom is bonded only to carbon atoms with a salt of a boron-hydride anion. 7. A process as defined in claim 6 wherein said boronhydride anion is B9H14 B3H3 B oH B l 112 io 14 4, m rs' z i'l ic rs s or B H CEN=.

References Cited Parry et a1.: J.A.C.S., volume 80, 1958, pages 24 to 27. CHARLES B. PARKER, Primary Examiner.

JOSEPH P. BRUST, Examiner.

S. T. LAWRENCE III, Assistant Examiner. 

